Feline Immunodeficiency Virus, or FIV, is a virus that attacks a cat’s immune system, making them susceptible to secondary infections caused by common bacteria, viruses and other pathogens. It is very similar to HIV in humans, in that it causes acquired immune deficiency syndrome (AIDS) over time, but healthy cats with FIV are largely asymptomatic and can lead normal, healthy lives for years before showing signs of disease. It is also a feline-only disease - it cannot spread to humans or other species living in your home.

How FIV is spread

FIV is most commonly spread through bite wounds incurred during catfights. For this reason, unneutered males who are allowed to roam outdoors are most commonly infected. Very rarely, a female cat can pass it to her kittens, but again, the most common way that FIV is spread is through bite wounds. Casual contact does not spread disease.

Signs and symptoms 

Once infected, the virus enters the lymph nodes, where it reproduces in T-lymphocytes and then spreads to other lymph nodes. During this time, you may notice enlarged lymph nodes or a fever in your cat. These signs are easy to miss, though, so it’s not unusual for phase of disease to go completely unnoticed.

From there, the health of a cat with FIV may be affected intermittently or may deteriorate progressively. Poor fur coat, gingivitis, persistent fever, recurrent skin, urinary tract and upper respiratory infections, and slow but progressive weight loss can all be blamed on FIV. Certain kinds of cancers are also more common in cats with FIV.

But as I said earlier, most cats with FIV show no signs at all in the early stages of disease, so it is not uncommon for a cat to go undiagnosed for extended periods. These cats, though infected, may appear healthy for years before their immune system is suppressed enough to slow them down. This is why many households may be unknowingly harboring the disease.

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Testing for FIV is relatively easy. Your veterinarian should have a simple blood test that he or she can perform in the office. If the test is positive, your veterinarian may want to send your cat’s blood out to an outside laboratory to confirm. It is important to remember that it takes 8 to 12 weeks after infection for antibody levels to increase to a level high enough to be detected – so if your cat has sustained bite wounds, testing for FIV right away will be fruitless.


There are no specific treatments that have been shown to affect the health or lifespan of healthy FIV-positive cats. Treatment of sick cats centers on the secondary infections that may occur as a result of the weakened immune system (respiratory or skin infection, for example). Human antiviral drugs may help cats with seizures or gingivitis, but otherwise do not show the promise that they do for human AIDS patients.

Jan 31, 2014
Pet Health

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